EXCAVATION What is excavation ? Marking a hole or tunnel by digging the ground by man or machine is called excavation
hseinfoquiz.com
Excavation hazard 1. Striking buried services / Underground
utilities.
2. Collapse / cave-ins.
3. Hazardous substances/Flammable & / or toxic gas release.
4. Lack of Oxygen or asphyxiation.
5. Flooding.
6. People or objects falling in.
7. Collapse of adjacent structures.
such as pipelines and electrical cables, are a potential hazard during excavations.
Before any excavation can begin, you must call concern department .Utility operators will mark underground utilities to verify their location before you begin to excavate the worksite to prevent accidental damage.
Underground utilities,
Many excavation fatalities are because of cave-ins.
Cave-ins pose the greatest risk and are much more likely to result in worker fatalities than other excavation-related accidents.
cave-ins
Workers die when they cannot breathe because the weight of collapsed materials prevents their chest from expanding.
Chest constriction prevents your body from taking in oxygen and releasing carbon dioxide.
Hazardous substances
Airways
Lungs
Diaphragm
When oxygen deficiency or a hazardous atmosphere exists or could exist in an excavation greater that 4 ft. in depth, the atmosphere must be tested before workers enter.
Oxygen deficient atmospheres are atmospheres that contain less than 19.5% oxygen.
oxygen deficiency
Take precautions to prevent water from collecting in an excavation. This is done by designing:
Diversion ditches
Dikes
Pumps
Other ways to stop water from building up within an excavation
Flooding
Precautions
• Battering • Shoring • benching • Prevention of striking buried services • Excavation area should be suitable barricade • Good lighting • Avoid heavy vehicle coming near the sides • Issue permit before start the work • Ladders shall be provided every 7.5 meters (25 feet) of
lateral travel in the trench • Ladders shall be securely supported at the bottom as well
as at the top • Gas test by the competent person.
Requirement
Daily and before the start of each shift.
As dictated by the work
being done in the trench.
After every rain storm and
other events that could
increase hazards, e.g.,
snowstorm, windstorm,
thaw, earthquake, etc.
Inspections – Competent Person
Frequency of testing should be increased if equipment is operating in trench as well as if welding, cutting, or burning is done in trench.
Inspections
Walkways provided when crossing over excavation.
Standard guardrail
installed when more
than 6 feet above
a lower level.
Fall Protection
What is shoring?
A structure that supports the sides of an excavation and protects against cave-ins.
What is Battering ?
The sides of the excavation can be sloped back (battered) at an angle that is sufficiently shallow that the soil will not slip.
What is Benching
Benching system means a method of protecting employees from cave-ins by excavating The sides of an excavation to form one or a series of horizontal levels or steps, usually With vertical or near-vertical surfaces between levels.
Timber Shoring
Aluminum Hydraulic
Trench Boxes
Pneumatic Systems
Type of excavation A. Manual Excavation: The excavation without using any powered
equipment.
B. Mechanical Excavation: The excavation work using any electrical or mechanical
What is the maximum distance between two adjacent accesses in a long excavation?
answer: A ladder must be present within 25feet, of employees working in excavation.
In open excavation – At least every 30m on the perimeter, if less than 1.2m deep.
At every 7.5m on the perimeter, if more than 1.2m deep.
Stable rock Type A
Classify the soil type:
Type B Type C
Cohesive soil
Clay, or soil with a high clay content, which has cohesive strength
Does not crumble
Can be excavated with vertical side slopes
Plastic when moist
Hard to break up when dry
Definitions
Granular soil
Gravel, sand, or silt, with little or no clay content
No cohesive strength
Cannot be molded when moist
Crumbles easily when dry
Note: Some moist granular soils exhibit
apparent cohesion
Definitions
Unconfined compressive strength
Load per unit area at which a soil will fail in compression
Note: Estimated in the field by use of a pocket penetrometer, thumb penetration test, and other methods
Definitions
Soil slope
• Roll into thread
• At least 2 inches in length
• Longer unbroken thread means more cohesive
Thread Test
• Roll soil into a cigar shape
• Pinch between thumb and finger
• Longer ribbon means more cohesive
Ribbon Test
Thumb Penetration Test
Pocket Penetrometer
Access and egress
Excavation
Ramp, ladder or stairs required at 4 feet or deeper.
25 feet 25 feet
Test at 4 feet if suspected
Hazardous Atmospheres
• LEL
• Oxygen
• CO
• H2S
• Petroleum
• Other toxics
Personal protective equipment (PPE) that may be required depending on the type of work includes:
Hard hats
Protective footwear
Gloves
Safety glasses with sideshields
Hearing protection
Fall protection
PPE
Emergency rescue equipment must be readily available where hazardous atmospheric conditions exist or expected to develop during work.
• Breathing apparatus
• Safety harness and line
• Basket stretcher
Emergency Rescue Equipment
Emergency Rescue Equipment
hseinfoquiz.com
Badshah
hseinfoquiz.com